Interior and exterior angles of regular polygons

I can find the interior and exterior angles of regular polygons.

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Year 8

Interior and exterior angles of regular polygons

I can find the interior and exterior angles of regular polygons.

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Lesson details

Key learning points

Exterior angles of a regular polygon are equal.
The size of the exterior angle of a regular polygon can be determined.
Interior angles of regular polygons are equal.
The size of the interior angle of a regular polygon can be determined.
The number of sides in a regular polygon can be determined from the size of the interior or exterior angle.

Common misconception

Pupils may solve angle problems by using methods which are less efficient than others.

While less efficient methods are fine, encourage pupils to review their work each time they solve a problem to consider alternative methods.

Keywords

Polygon - A polygon is a flat (2D), closed figure made up of straight line segments.
Regular polygon - A regular polygon has sides that are equal and interior (inside) angles that are all equal.
Interior angle - An interior angle is an angle formed inside a polygon by two of its edges.
Exterior angle - An exterior angle is an angle on the outside of a polygon between an extension of an edge and its adjacent edge.

One of the slides contains a link to a GeoGebra activity similar to what Sofia uses. If pupils have access to web browsers, they could use it to perform a similar investigation by attempting to draw regular polygons using different exterior angles.

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Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).